Coffee husks and coffee pulp are the solid residue obtained after dehulling coffee cherries during processing. The structure of these coffee cherries is well known, as described herein.
FIG. 1 shows a cross sectional view of the fruit of a coffee tree, i.e., “1” shows a “coffee cherry.” Moving from the outermost layer toward the center, one has the outer skin “7,” the “pericarp” or “exocarp,” then pulp “6,” also referred to as “mesocarp,” followed by a pectin layer “5,” parchment or endocarp “4”, silverskin “3,” (also referred to as the “testa” or “epidermis”), and finally the coffee beans, or endosperm “2”. Usually, each coffee cherry contains two beans which, as is seen in FIG. 1, face each other, with flat sides abutting each other.
Coffee production requires removal of the coffee beans “2” from the coffee cherry, prior to roasting the beans.
Generally, two broad methodologies are known and used for processing the coffee cherries, i.e., the “dry method” and the “wet method.”
In brief, historically what is termed the “dry method” has been and is used in countries where water resources are limited. The coffee cherries are spread out on vast surfaces to dry in the sun, and raked and turned throughout the day and covered at night or during rain to prevent them from getting wet until the moisture content of the cherries decreases to approximately 11%.
Alternatively, processing is accomplished by what is termed the “wet method”. In summary, the wet method involves removal of the pulp from the coffee cherry and drying the bean with the parchment skin left on. To elaborate, first, freshly harvested coffee cherries are passed through a pulping machine to separate the skin and pulp from the beans. The beans are then separated by weight as they pass through water channels, with the lighter beans floating to the top and heavier beans sinking to the bottom. After passing the beans through a rotating drum to separate them by size, they are transported to a water filled fermentation tank at which point the slick layer of mucilage is removed through fermentation processes. When this is complete, the beans are rinsed and ready for drying.
If processed via the wet process, the beans are still inside the parchment envelope (the endocarp). The beans are dried and these dried beans are then known as parchment coffee. This is in contrast to dry method processing, where all non-bean elements are removed in one step.
Before being exported, parchment coffee typically, but is not necessarily, processed by using a hulling machine which removes the endocarp, thus leaving the exocarp, mesocarp, and endocarp as waste material.
In each case, the goal is to separate the material covering the beans, that is, the outer skin, pulp and parchment, which together, are often referred to as coffee husks.
It has been suggested that there could be significant advantages in finding uses for what is now considered the waste product, i.e., the coffee husks or parts thereof such as the parchment.
One of the significant problems is that both coffee husks and coffee pulp contain organic matter including caffeine, tannins, and polyphenols. Polyphenols are toxic and thus use of materials containing these is restricted. Also, caffeine is a powerful stimulant and is therefore considered to be a negative constituent for, e.g., animal feed.
Although there has been experimental use of coffee husks for uses including livestock feed, silage, composting, biofuels, ethanol production and creation of biogas, none of these processes has resulted in commercially viable products, either because they are unsuitable, per se or, because the cost of modifying them to permit them to be suitable exceeds the current value for the replacement of other pre-existing products.
The patent literature in the art exemplifies the interest in this field of technology. Exemplary of U.S. Pat. Nos. 7,311,864; 7,927,460; 4,379,844; 3,927,235; 4,364,979; and 3,686,384. Exemplary published U.S. Patent Applications include U.S. 2007/0043937; 2007/0065397; and 2015/0354143, and international applications WO 20130556221 and WO 2014081093. The non-U.S. patent literature is extensive and is exemplified by KR 1578324; AU 679190; GB 664848; KR 1703961; JP 03170124; DE 10114341; CN 106223090; CN 106192596; JP 2009167536; JP 2012082550; JP 04296408; JP 04928904; JP 4082999; JP 57014794; JP 7327537; TW 201604350; JP 8070724; JP 8158298; JP 7238488; JP 8029351; JP 10248409; CN 106087521; CN 106087522; KR 1210418; KR 1344471; KR 2011050156; KR 2015028029; CN 106522022; CN 104928979; CN 104947409; and JP 56129157. Attention is drawn in particular to U.S. 20170043937 and U.S. Pat. No. 7,311,864, as well as KR 1578324 and AU 679190. All of these are incorporated by reference in their entirety.
Notwithstanding the considerable literature in this field, the art still needs a method for utilizing the vast amounts of waste materials produced in the manufacture of coffee.
According to the present invention, the waste material of the coffee parchment is purged of polyphenols generally present in the tannins and the resultant fibrous material is retained.
Based on the similarities between the conventional raw materials used in filter making (soft woods like pine and spruce), which are characterized by long, thin cellulose filters and the parchment skin discussed here, which contains shorter, and thicker cellulose fibers, it is presumed that the coffee waste material can be substituted at levels above 50% or at any higher or lower level which suits the user. The chart below illustrates this point (bamboo is another raw material that is presently being used in the manufacturing of filters):
Analysis of composition of Botanical MaterialsScotts Norway Coffee PineSpruceParchmentBambooCellulose40.7%42.0%44.5%47.3%Hemicellulose26.9%27.3%28.5%23.5%Ligni27.027.4%34.0%22.1%Extractives5.0%2.0%Ash0.8%1.9%
The fibrous material is then in turn fabricated into a filter material for use into a coffee filter for brewing coffee. Alternatively, the fibrous parchment material can be fabricated into other paper products such as “sleeves” for holding a cellulose based coffee cup, paper containers or cans (e.g., composite cans) to store and/or serve as packaging for coffee beans, ground coffee so-call “K-cups” as represented by, e.g., U.S. Pat. Nos. 5,325,765; 5,840,189; and 5,637,335, which are incorporated by reference. The fibrous parchment material can also be mixed with other materials, e.g., other wood pulp(s) or recycled paper to form various paper products, such as milk or other beverage containing disposable cups, and so forth. For example, the fibrous material can be fabricated with other cellulosic materials, such as wood pulp fiber, soft wood fiber in particular, and may optionally include up to 1% of a binder material, to produce corrugated cardboard that is suitable, e.g., for the packaging of shipped goods, storage boxes, among other uses. Alternatively, the fibrous parchment material can be fabricated into a paper board material which is suitable for producing paper trays, or paper cores/spools for paper towels, toilet paper, plastic/film/foil wraps or rolls, or other goods which are generally wrapped about a paper core, among other goods/products that use paper board for packaging purposes.
Without limiting the applicability or methodology, the removal of the polyphenolic compounds from plant extracts can be accomplished by using methods such as those described in Geremu, et al., Chem. Biol. Technol. Agric., 3:25(2016), and Collins, et al., Biochemistry and Molecular Biology International, 45(4):791-796 (1998), both of which are incorporated by reference, or such other method as shah be known to a person of ordinary skill in the art.
The material can be fabricated into either fibers or sheets with porosity, absorption and adsorption characteristics suitable for filtration.
The foregoing discussion applies to wet method processed coffee. If dry method is employed, the parchment is first separated from the other waste material and then processed as described.